1. Technical Field
The present disclosure generally relates to a touch panel, and more particularly to a capacitive touch panel structure with high throughput and sensitivity.
2. Description of Related Art
The typical capacitive touch panel mainly includes a capacity structure which is formed with two layers of Indium Tin Oxide (ITO) films and an insulating layer. When touching the touch panel by fingers to interference the electric field, the capacitance of the capacity structure may be changed. Detect the capacitance variations by driving and reading circuits, and the position of the touch point will be determined. FIG. 1A is a schematic diagram showing the patterned ITO film of a typical capacitive touch panel. Wherein, the diamond patterns of the ITO film 10A disposed on the top level and the ITO film 10B disposed on the bottom level are crisscross. Regarding the touch panel structure of FIG. 1A, the ITO films 10A, 10B disposed on the top level and the bottom level must be driving respectively to obtain the touch point. However, when touching at two touch points simultaneously, it cannot make sure of the positions of all touch points. FIG. 1B is a schematic diagram showing the patterned ITO film of another typical capacitive touch panel. Wherein, the overlapping region of the rectangular patterns of the ITO film 12A disposed on the top level and the ITO film 12B disposed on the bottom level may be defined a plurality of detection area. One or more touch points can be detected by driving one layer of the ITO film.
Whether the typical capacitive touch panel shown in FIG. 1A or FIG. 1B, semiconductor manufacturing techniques such as lithography, exposure and etching are utilized to form the patterning of the ITO films thereof. Many steps may be processed multifariously during manufacturing process, therefore causing it to be unable to improve the efficiency of the touch panel and to decrease the manufacturing cost and time. Moreover, due to the restriction of resolution of manufacturing process, it is unable to breaks through the bottleneck over the sensing precision of the typical touch panel.
Accordingly, the carbon nanotube (CNT) films are used to substitute for the ITO films recently. The CNT film has anisotropic impedance, i.e., its impedance in a first direction is least but in a second direction which is perpendicular to the first direction is biggest. FIG. 1C is a schematic diagram showing the capacitive touch panel with CNT films, which mainly includes a top layer of CNT film 14A, a bottom layer of CNT film 14B and an insulating layer disposed between the CNT films 14A, 14B. Wherein, the direction of the least impedance of the top layer of CNT film 14A is perpendicular to the direction of the least impedance of the bottom layer of CNT film 14B. The throughput of the CNT capacitive touch panel shown in FIG. 1C is greater than the ITO capacitive touch panels shown in FIG. 1A, 1B. However, when touching the touch panel, the electric fields of two layers of CNT films 14A, 14B are not easy to be interfered, and it causes that the capacitance variation is too small to improve sensitivity.
Accordingly, a need has arisen to propose a novel capacitive touch panel with high throughput and sensitivity.